What is the baseline of the FHT? A concern with continuous EFM is the lack of standardization in the FHR tracing interpretation.5,811 Studies demonstrate poor inter-rater reliability of experts, even in controlled research settings.12,13 A National Institute of Child Health and Human Development (NICHD) research planning workshop was convened in 1997 to standardize definitions for interpretation of EFM tracing.14 These definitions were adopted by the American College of Obstetricians and Gynecologists (ACOG) in 2002,5 and revisions were made in a 2008 workshop sponsored by NICHD, ACOG, and the Society for Maternal-Fetal Medicine.11 The Advanced Life Support in Obstetrics (ALSO) curriculum developed the mnemonic DR C BRAVADO (Table 3) to teach a systematic, structured approach to continuous EFM interpretation that incorporates the NICHD definitions.9,11. Your doctor can then take steps to manage the underlying medical problem. Symmetrical gradual decrease and return of the FHR associated with a uterine contraction. Please try reloading page. a. Impact of maternal exercise during pregnancy on offspring chronic disease susceptibility. MedlinePlus. . What are the two most important characteristics of the FHR? She specializes in health and wellness writing including blogs, articles, and education. Scalp. Differentiate maternal pulse from fetal pulse, 4. Your doctor will explain the steps of the procedure. contraction. Compared with EFM alone, the addition of fetal electrocardiography analysis results in a reduction in operative vaginal deliveries (NNT = 50) and fetal scalp sampling (NNT = 33). Am I Having Depression During Pregnancy? Early. The EFM toolkit also offers EFM CE opportunities and C-EFM(R) certification information. < 32 weeks EGA: peak 10 bpm above baseline, duration 10 seconds but < 2 minutes from onset of the acceleration to return to baseline. When the healthcare team detects a possible problem, their first step will be to try to find the cause. With a Doppler ultrasound, for example, an ultrasound probe is fastened to your stomach. A. NICDH definitions of decelerations: Understanding the physiology of fetal oxygenation and various influences on fetal heart rate control supports nurses, midwives, and physicians in interpreting and managing electronic fetal heart rate tracings during labor and birth. Dont be overly alarmed if you dont hear your babys heartbeat by 10 or 11 weeks. Continuous electronic fetal monitoring has been shown to reduce the incidence of neonatal seizures, but there has been no beneficial effect in decreasing cerebral palsy or neonatal mortality. Garite TJ, Dildy GA, McNamara . Corticosteroid administration may cause an increase in FHR accelerations. Correct. What are the two most important characteristics of the FHR? The average fetal heart rate varies depending on the stage of pregnancy. -often *correctable by changes in maternal position to relieve pressure* on cord Relevant ACOG Resources. Count FHR between contractions for 60 seconds to determine average baseline rate, 6. Challenge yourself every tracing collection is FREE! contraction Continuous electronic fetal monitoring was developed in the 1960s to assist in the diagnosis of fetal hypoxia during labor. Theyre empowered by these results to intervene and hopefully prevent an adverse outcome. 3. Theyll wrap a pair of belts around your belly. Coussons-Read ME. Healthcare providers usually start listening for a babys heart rate at the 10- or 12-week prenatal visit. Effects of prenatal stress on pregnancy and human development: Mechanisms and pathways. In addition, you must know what is causing each type of deceleration, such as uteroplacental insufficiency or umbilical cord compression. The American College of Obstetrics and Gynecologists. Healthcare providers usually start listening for a baby's heart rate at the 10- to 12-week prenatal visit using a Doppler machine. This depends on the source and duration of your increased heart rate. The electronic fetal monitor uses an external pressure transducer or an intrauterine pressure catheter (IUPC) to measure amplitude and frequency of contractions. Additionally, you may have difficulty detecting the heart rate even when the baby is perfectly fine. - 100-110 can be sustained for long periods if normal variability Light application of water to a turfgrass. Normal variations in fetal heart rate occur when the baby is moving or asleep. These settings will apply for this game only and take precedence over Global Settings that are set on the Customize page. Monitoring the fetal heart rate more often can be helpful in high-risk pregnancies. Palpate the abdomen to determine the position of the fetus (Leopold maneuvers), 2. Fetal heart monitoring. 2023 Annual Clinical & Scientific Meeting, Congressional Leadership Conference (CLC), Countdown to Intern Year, Week 4: Fetal Heart Tracings, Intrapartum Fetal Heart Rate Monitoring: Nomenclature, Interpretation, and General Management Principles, Management of Intrapartum Fetal Heart Rate Tracings, Anti-Racism Resources: Articles, Videos, Podcasts, Novels Etc, Alliance for Innovation on Maternal Health, Postpartum Contraceptive Access Initiative, Baseline fetal heart rate (FHR) variability, Changes or trends of FHR patterns over time, Frequency and intensity of uterine contractions, Normal: five contractions or less in 10 minutes, averaged over a 30-minute window, Tachysystole: more than five contractions in 10 minutes, averaged over a 30-minute window, Always include presence or absence of associated FHR decelerations, Applies to both spontaneous and stimulated labor. Weve also included information on the #OBGYNInternChallenge via @Creogsovercoffee. 2023 National Certification Corporation. Intrapartum fetal monitoring was developed in the 1960s to identify events that might result in hypoxic ischemic encephalopathy, cerebral palsy, or fetal death. Remember, the baseline is the average heart rate rounded to the nearest five bpm. This measurement helps healthcare providers determine the well-being of the fetus during prenatal visits or labor. Data from: Macones GA, Hankins GD, Spong CY, et al. Write a program that checks whether a sequence of HTML tags is properly nested. https://obgyn.onlinelibrary.wiley.com/doi/pdf/10.1016/j.ijgo.2015.06.020 It provides your healthcare team with information so they can intervene, if necessary. Rate and decelerations B. Give amnioinfusion for recurrent, moderate to severe variable decelerations, 9. The Value of EFM Certification (One Team One Language), showcases the national PSA campaign Your Baby Communicates along with peer-to-peer video discussions on the value of EFM Board Certification. This fetal heart rate quiz will test your knowledge about fetal decelerations during labor. | Terms and Conditions of Use. abrupt: onset to nadir <30 sec, *uterine contractions/fetal head compression* -pressure on fetal head U.S. Food and Drug Administration. Marked. most common cause of tachysystolic or hypertonic contractions: oxytocin + prostaglandins, Julie S Snyder, Linda Lilley, Shelly Collins, Linda Bucher, Margaret M Heitkemper, Mariann M Harding, Shannon Ruff Dirksen, Sharon L Lewis. Conversely, hearing a fetal heart rate by home Doppler in certain situations may provide a false sense of security when medical attention is actually needed. Category I FHR includes all of the following: baseline: 110-160 bpm Detection is most accurate with a direct fetal scalp electrode, although newer external transducers have improved the ability to detect variability. It takes that professionals understanding of what the continuous tracings show to properly assess the fetal condition. 1. Place the Doppler over the area of maximal intensity of fetal heart tones, 3. Fetal heart tracing is also useful for eliminating unnecessary treatments. See our full, Click to share on Facebook (Opens in new window), Click to share on Twitter (Opens in new window), Click to share on Pinterest (Opens in new window), Click to share on Reddit (Opens in new window), Click to share on LinkedIn (Opens in new window), Click to share on WhatsApp (Opens in new window), Click to share on Pocket (Opens in new window), Click to share on Telegram (Opens in new window), Click to share on Skype (Opens in new window), IV Drug Use Complications & Dangers: (Endocarditis, Infection, Infectious Diseases). If the heart rate is out of the normal range, the team can do an ultrasound or order blood work. Accelerations (A). The Fetal Heart Rate Tracing SecondLook application is a study aid for learners of the medical professions (specifically Ob/Gyn, nursing and midwifery) to self-test their level of knowledge about this important diagnostic procedure used in pre-natal care. coincides with the peak of Fetal heart tracing allows your doctor to measure the rate and rhythm of your little one's heartbeat. It is important to recognize that FHR tracing patterns provide information only on the current acidbase status of the fetus. A stethoscope or fetoscope can be used by anyone after 20 or 22 weeks of pregnancy. Typically performed in the later stages of pregnancy and during labor, fetal heart tracing results can say a lot about the health of your baby. Give intravenous fluids if not already administered; consider bolus, 7. This fetal heart rate quiz will test your knowledge about fetal decelerations during labor. 30 min-2hrs Here's generally what to expect: Weeks 10 to 12 of pregnancy are very exciting for expectant parents. Compared with structured intermittent auscultation, continuous EFM showed no difference in overall neonatal death rate. -*hypertonus*: abnormally high resting tone >25 mmhg or MVU >400 During a term antepartum NST (non-stress test), you notice several variable decelerations that decrease at least 15 bpm and last at least 15 secs long. Content adapted from relevant ACOG Practice Bulletins and AAFP Guidelines. Needs immediate intervention; may be due to severe fetal anemia, abdominal trauma or serious fetal infection. These are called maternal causes and may include: The following methods are used to listen to a fetal heart rate: External monitoring means checking the fetal heart rate through the mothers abdomen (belly). Therefore, it is a vital clue in determining the overall fetal condition. They really aren't intended for home monitoring. Your obstetrician reviews the fetal heart tracing at regular time intervals. Healthcare providers monitor fetal heart rate during labor to watch how the baby responds to contractions, medications, tests, and pushing. The use of amnioinfusion for recurrent deep variable decelerations demonstrated reductions in decelerations and cesarean delivery overall. Reviewed by Eugenia Tikhonovich, MD Obstetrician-Gynecologist, Medical Consultant - When considering the effectiveness of Electronic Fetal Monitoring, it comes down to the experience and knowledge of the person identifying the tracings. She lives with her husband and springer spaniel and enjoys camping and tapping into her creativity in her downtime. Visually apparent, abrupt (onset to peak < 30 seconds) increase in FHR from baseline. Management depends on the clinical picture and presence of other FHR characteristics.18, Overall Assessment (O). Whats a Normal Fetal Heart Rate During Pregnancy? Buttocks. Electronic fetal monitoring is used to record the heartbeat of the fetus and the contractions of the mother's uterus before and during labor. Prolonged decelerations (Online Figures K and L) last longer than two minutes, but less than 10 minutes.11 They may be caused by a number of factors, including head compression (rapid fetal descent), cord compression, or uteroplacental insufficiency. Fluorescent-labeled lineage tracing revealed that 1 week after transplantation, green fluorescent protein (GFP)-MSCs were found to migrate to the bone surface (BS) in control mice but not in DIO mice. Depending on your health status and your babys, nonstress tests (one to two times a week, if not daily) might be a good idea. Baseline rate: 110 to 160 bpm . This web game uses NICHD terminology to identify tracing elements and categorize EFM tracings. Your program should process a International Journal of Gynecology & Obstetrics. That being said, its still critical for you to know how to interpret a strip. Practice Quizzes 1-5 - Electronic Fetal Monitoring Basic and Advanced Study Home About Self Guided Tutorial EFM In-Depth Assessments Fetal Tracing Index References Practice Quizzes 1-5 Try your hand at the following quizzes. Baseline is calculated as a mean of FHR segments that are the most horizontal, and also fluctuate the least. For more information on the use, interpretation and management of patients based on Fetal Heart Tracings check out the resources below. What does it mean to have a "reactive strip"? A fetal heart rate gives you and your healthcare team information about your baby's health during pregnancy. Sometimes a fetal heart rate is outside the normal range simply because the fetus is moving around. A gradual decrease is defined as at least 30 seconds from the onset of the deceleration to the FHR nadir, whereas an abrupt decrease is defined as less than 30 seconds from the onset of the deceleration to the beginning of the FHR nadir.11, Early decelerations (Online Figure H) are transient, gradual decreases in FHR that are visually apparent and usually symmetric.11 They occur with and mirror the uterine contraction and seldom go below 100 bpm.11 The nadir of the deceleration occurs at the same time as the peak of the contraction. Maternity Nursing Lecture Fetal Heart Rate Decelerations: This video explains fetal heart rate tone decelerations (early decelerations, late decelerations , . --recurrent variable decels Copyright 2009 by the American Academy of Family Physicians. 2023 Dotdash Media, Inc. All rights reserved, Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Baseline Johns Hopkins Medicine. Continuous EFM increased cesarean delivery rates overall (NNH = 20) and instrumental vaginal births (NNH = 33). To provide a systematic approach to interpreting the electronic fetal monitor tracing, the National Institute of Child Health and Human Development convened a workshop in 2008 to revise the accepted definitions for electronic fetal monitor tracing. Fetal heart tracing allows your doctor to measure the rate and rhythm of your little ones heartbeat. Yes. Tracing patterns can and will change! Moderate. It provides more precise readings that are not affected by the babys movement. Tracings of the normal fetal heart rate are between 120 and 160. View questions only 3/10/2017 Fetal Heart Tracing Quiz 1 Correct. Talk with your healthcare provider if you're concerned about your babys heart rate or if your pregnancy is high-risk. At 12 h after incubation, the cells on the . presence of at least *2 accels, lasting for 15+ seconds* above baseline and peaking at 15+ bpm in a *20 min window*, >25 bpm variation Maladaptive Daydreaming Test: Am I A Maladaptive Daydreamer? Am J Obstet Gynecol 1981; 140:435. She is the former chief of obstetrics-gynecology at Yale Health. -medicated through vagus nerve w sudden release of ACh at fetal SA node, resulting in characteristic sharp decel It's typically the first time they hear their babys heartbeat during a prenatal visit. A person viewing it online may make one printout of the material and may use that printout only for his or her personal, non-commercial reference. Structured intermittent auscultation is a technique that employs the systematic use of a Doppler assessment of fetal heart rate (FHR) during labor at defined timed intervals (Table 1).4 It is equivalent to continuous EFM in screening for fetal compromise in low-risk patients.2,3,5 Safety in using structured intermittent auscultation is based on a nurse-to-patient ratio of 1:1 and an established technique for intermittent auscultation for each institution.4 Continuous EFM should be used when there are abnormalities in structured intermittent auscultation or for high-risk patients (Table 2).4 An admission tracing of electronic FHR in low-risk pregnancy increases intervention without improved neonatal outcomes, and routine admission tracings should not be used to determine monitoring technique.6. This technique is considered only after a mother's water has broken and the cervix is dilated or open. Baseline Rate (BRA; Online Table B). Electronic fetal monitoring may help detect changes in normal FHR patterns during labor. -*considered significantly non-reassuring, esp when repetitive and associated w decreased variability*, Repetitive late decelerations are defined as, occurring *after 50%+ of contractions in a 20 min* period, *uteroplacental insufficiency*, as a result of eitehr decreased uterine perfusion or decreased placental function A baseline of less than 110 bpm is defined as bradycardia.11 Mild bradycardia (100 to 110 bpm) is associated with post-term infants and occipitoposterior position.15 Rates of less than 100 bpm may be seen in fetuses with congenital heart disease or myocardial conduction defects.15 A baseline greater than 160 bpm is defined as tachycardia11 (Online Figure B). Fluctuations in the baseline FHR that are irregular in amplitude and frequency. -amnioinfusion can treat it in cases of oligohydramnios or when ROM has occurred to decrease rate of decels and C-sections, Recurrent decel (variable, early, late) defined as, decels occuring w >50% of uterine contractions in any 20 min segment, decrease in FHR >15 bpm measured from most recently determined baseline rate, *lasting >2 min, but <10 min* The onset, nadir, and recovery of the deceleration usually coincide with the beginning, peak, and ending of the contraction, respectively.11 Early decelerations are nearly always benign and probably indicate head compression, which is a normal part of labor.15, Variable decelerations (Online Figure I), as the name implies, vary in terms of shape, depth, and timing in relationship to uterine contractions, but they are visually apparent, abrupt decreases in FHR.11 The decrease in FHR is at least 15 bpm and has a duration of at least 15 seconds to less than two minutes.11 Characteristics of variable decelerations include rapid descent and recovery, good baseline variability, and accelerations at the onset and at the end of the contraction (i.e., shoulders).11 When they are associated with uterine contractions, their onset, depth, and duration commonly vary with successive uterine contractions.11 Overall, variable decelerations are usually benign, and their physiologic basis is usually related to cord compression, with subsequent changes in peripheral vascular resistance or oxygenation.15 They occur especially in the second stage of labor, when cord compression is most common.15 Atypical variable decelerations may indicate fetal hypoxemia, with characteristic features that include late onset (in relation to contractions), loss of shoulders, and slow recovery.15. Early fetal development. Compare maternal pulse simultaneously with FHR, According to AWHONN, the normal baseline Fetal Heart Rate (FHR) is. Fetal bradycardia is defined as a baseline heart rate of less than 110 bpm. This article reviews normal fetal heart rate, how it is measured, who should monitor it, and what causes variations. What are the rate and duration of the contractions seen on this strip?What intervention would you take after evaluating this strip? Every piece of content at Flo Health adheres to the highest editorial standards for language, style, and medical accuracy. Auscultation of the fetal heart rate (FHR) is performed by external or internal means. However, the strength of contractions cannot always be accurately assessed from an external transducer and should be determined with an IUPC, if necessary. - 80-100 is non reassuring, <80 is ominous and may presage death However, FHR with low-quality signals may somehow exaggerate the risk of the fetus suffering from acidemia, thus contributing to an increase in cesarean section rates. It can provide lots of information about your babys health during pregnancy. file containing tags. Fetal heart rate monitoring during labor. The FHR normally exhibits variability, with an average change of 6 to 25 bpm of the baseline rate, and is linked to the fetal central nervous system. ____ Prolonged D.)Gradual decrease; nadir The baseline will be stable with a ten-beat variability, for instance 120 to 130, or 134 to 144. > 2 min., but < 10 min in A wooden artifact is found in an ancient tomb. The normal range for baseline FHR is defined by NICHD as 110 to 160 beats per minute (bpm; Online Figure A). Patient information: See related handout on electronic fetal monitoring, written by the author of this article. When you've finished these first five, here are five more. What happens if my prenatal doctor hears a fetal heart arrhythmia? According to an executive from Vitalant, the largest nonprofit blood bank in the United States, as much as 80% of the blood supply is from vaccinated donors. Fetal Heart Tracing Quiz 1 FHT Quiz 1 Fetal Tracing Quiz Please answer each question. BJOG: An International Journal of Obstetrics & Gynaecology. The first uses Doppler ultrasound to monitor FHR patterns, while the second measures the duration and frequency of uterine contractions. Question 1: Sinusoidal fetal heart rate (cat iii FHR tracing) = repetitive, wave like fluctuations with absent variability and no response to contractions. Print Worksheet. *NO late or variable decels* No. -early labor: 0-6cm, 6-12 hours UT Southwestern Medical Center. https://www.acog.org/~/media/For%20Patients/faq015.pdf. Registered Nurse, Free Care Plans, Free NCLEX Review, Nurse Salary, and much more. While it can be an important tool to assess fetal wellbeing, it is also limited by its high false-positive rate. Furthermore, you will need to know what causes these decelerations to happen and if you need to intervene as the nurse. *nonreflex*: greater degree of relative hypoxemia and result in hypoxic depression of myocardium coupled w vagal response In 2013, researchers proposed an algorithm for the management of category II fetal heart tracings. Cross) Civilization and its Discontents (Sigmund Freud) Forecasting, Time Series, and Regression (Richard T. O'Connell; Anne B. Koehler) If delivery is imminent, even severe decelerations are less significant than in the earlier stages of labor. Decrease in FHR from the baseline that is 15 bpm or more, lasting 2 minutes or more but less than 10 minutes in duration. You have to lie down or sit in a reclined position for the test, which lasts about 20 minutes. to access the EFM tracing game and to take full advantage of all the resources available. In addition, you must know what is causing each type of deceleration, such as uteroplacental insufficiency or umbilical cord compression. Late decelerations (Online Figure J) are visually apparent, usually symmetric, and have the characteristic feature of onset of the deceleration after the onset of the uterine contraction.11 The timing of the deceleration is delayed, with the nadir of the deceleration occurring after the peak of the contraction.11 The onset, nadir, and recovery of the deceleration usually occur after the beginning, peak, and ending of the contraction, respectively. Blaize AN, Pearson KJ, Newcomer SC. -acceleration in response means that acidosis is unlikely The perception that structured intermittent auscultation increases medicolegal risk, the lack of hospital staff trained in structured intermittent auscultation, and the economic benefit of continuous EFM from decreased use of nursing staff may promote the use of continuous EFM.8 Online Table A lists considerations in developing an institutional strategy for fetal surveillance. This web game uses NICHD terminology to identify tracing elements and categorize EFM tracings. Your JFAC wishes you the best of luck as you start this rewarding journey. The baseline when the woman's abdomen is relaxed will be from zero to 10. E Jauniaux, F Prefumo. ACOG recommends using a three-tiered system for the categorization of FHR patterns. Tracing patterns can and will change! fundal height 30 cm b. fetal movement count 12 kicks in 12 hours c. fetal heart rate 136/min d. . May 2, 2022 The NCC EFM Tracing Game is part of the free online EFM toolkit at NCC-EFM.org. (They start and reach maximum value in less than 30 seconds.) The Fetal Heart Rate Tracing SecondLookTM app will display a prompt if new updates are available for download. The main goal is to identify fetuses who are prone to injuries stemming from hypoxia (or a lack of oxygen for fetal tissues). A prenatal non-stress test (NST) can be used to assess fetal heart rate and movement at around 26 to 28 weeks of gestation. Causes, Symptoms, and Treatment, 2023 Flo Health Inc., Flo Health UK Limited, Ovulation calculator: Figure out your most fertile days, hCG calculator: How to track your hCG levels at home, Pregnancy test calculator: Figure out when a pregnancy test is most accurate, Period calculator: Predict when your next period will arrive. You have to lie down or sit in a reclined position for the test, which lasts about 20 minutes. --bradycardia Incorrect. Onset, depth, and duration commonly vary with successive uterine contractions. Must be for a minimum of 2 minutes in any 10-minute segment. EKG Rhythms | ECG Heart Rhythms Explained - Comprehensive NCLEX Review, Simple Anatomy Quiz Most Nurses Get WRONG! The workshop introduced a new classification scheme for decision making with regard to tracings. Fetal heart rate monitoring may be performed exter-nally or internally. The different catagories of FHR tracings and their clinical meanings are discussed. Absent. What kind of variability and decelerations are noted in this strip? It is important to review the pressure tracing before assessing the fetal tracing to accurately interpret decelerations. The NCC EFM Tracing Game is part of the free online EFM toolkit at NCC-EFM.org. The fetal heart rate and contraction information appear on an attached computer screen. Internal FHR monitoring is accom-plished with a fetal electrode, which is a spiral wire placed directly on the fetal scalp or other presenting part. Find the toco, or uterine contraction tracing, in the bottom half of the strip. A way to assess your babys overall health, fetal heart tracing is performed before and during the process of labor. Enter your email address below and hit "Submit" to receive free email updates and nursing tips. Fetal development. For example, if there is a drop in FHR, and then 30 seconds later it rises again, this is more likely a deceleration than a fetal bradycardia. determination of *fetal blood pH or lactate: scalp blood sample* Accelerations represent a sudden increase in FHR of more than 15 bpm in bandwidth amplitude. Tachycardia is certainly not always indicative of fetal distress or hypoxia, but this fetal tracing is ominous. Another area of interest is the use of computer analysis for key components of the fetal tracing,29 or decision analysis for the interpretation of the EFM tracing.30 These have not been demonstrated to improve clinical outcomes.29,30 Fetal pulse oximetry was developed to continuously monitor fetal oxygenation during labor by using an internal monitor, requiring rupture of membranes.31 Trials have not demonstrated a reduction in cesarean delivery rates or interventions with the use of fetal pulse oximetry.31. Prior . -variable decels w no other characteristics, -*absent baseline variability and any of following*: Krebs HB, Petres RE, Dunn LJ. This is a short reference on the physiologic benefits, instrumentation, application and interpretation of fetalheart rate monitoring. Remember, the baseline is the average heart rate rounded to the nearest five bpm.140 145 150 155 160 FHT Quiz 1 Fetal Tracing Quiz Perfect! Test your EFM skills using NCC's FREE tracing game! Positive Signs of Pregnancy Fetal heart sounds Palpation of fetal movement Visualization of fetus . It is common to have a baseline heart rate of between 100-120 bpm in the following situations: Postdate gestation Occiput posterior or transverse presentations Severe prolonged bradycardia (less than 80 bpm for more than 3 minutes) indicates severe hypoxia. A fetal heart rate greater than 160 beats per minute (BPM) is considered fast. --> decreased intervillous exchange of oxygen adn CO2 and progressive fetal hypoxia and acidemia, *abrupt, onset <30 sec* visually apparent decreases in FHR below baseline FHR The Fetal Heart Rate Tracing SecondLookTM application is a study aid for learners of the medical professions (specifically Ob/Gyn, nursing and midwifery) to self-test their level of knowledge about this important diagnostic procedure widely used in pre-natal care.