Comparative Study of Methods of Fetal Weight Estimation

Comparative Study of Methods of Fetal Weight EstimationINTRODUCTIONKnowledge of fetal angle in utero is important for the obstetricalian to decide whether or not to deliver the fetus and also to decide the mode of delivery. Both low comport system of weights and excessive fetal weight at delivery are associated with increased risk of newborn complications during labor and the puerperium. Various clinical looke akin Johnsons formula and break of days formula have come into usage for fetal weight estimation. An early(a) formula is the product of symphysiofundal bloom with abdominal girth in centimeters which gives a fairly uncorrupted estimate of fetal weight.METHODSIt is a prospective observational study of 200 women at term pregnancy at a hospital.Patients within 15 eld from their Expected Date of Delivery were included in the study. The formulas used in this study areJOHNSONS radiation diagramSYMPHYSIOFUNDAL HEIGHT X ABDOMINAL cinch (AG X SFH)DAWNS FORMULAHADLOCKS FORMULA USING ULTRASOUND.RESUTLSThere have been differing results about accuracy of various rules of estimating fetal weight. This study showed that AG X SFH was the best indicator among in all otherwise methods assessed followed by Hadlocks formula by ultrasonographic method.CONCLUSIONFundal height assessment is an inexpensive method for display for fetal growth restriction. SFH measurement continues to be used in many countries on large scale because of its low cost, ease of use, and need for little nurture as the setup for ultrasonographic evaluation is not readily available in rural setups.KEYWORDS Fetal Weight, At Term Pregnancy, Symphysiofundal Height, Ultrasonography, Newborn ComplicationsINTRODUCTIONKnowledge of fetal weight in utero is important for the obstetrician to decide whether or not to deliver the fetus and also to decide the mode of delivery. Both low birth weight and excessive fetal weight at delivery are associated with an increased risk of newborn complications dur ing labor and the puerperium. The perinatal complications associated with low birth weight are attributable to preterm delivery, intrauterine growth restriction (IUGR), or both. For excessively large fetuses, the potential complications associated with delivery include shoulder dystocia, brachial plexus injuries, lean injuries, and intrapartum asphyxia. The maternal risks associated with the delivery of an excessively large fetus include birth canal and pelvic floor injuries and postpartum hemorrhage. The occurrence of cephalopelvic disproportion is more prevalent with increase fetal size and contributes to both an increased rate of operative vaginal delivery and ces orbital cavityn delivery for macrosomic fetuses compared with fetuses of normal weight. Estimation of fetal weight beingness done clinically has received much criticism for slight accuracy due to observer variation.Various clinical formulae like Johnsons formula and Dawns formula have come into usage for fetal weight estimation. Another formula is the product of symphysiofundal height with abdominal girth in centimeters which gives a fairly good estimate of fetal weight.AIMS AND OBJECTIVESThe aim of this study was to assess the fetal weight in term pregnancies by various methods- abdominal girth (cms) X symphysiofundal height (cms) AG X SFH, Johnsons formula, Dawns formula and Hadlocks formula using ultrasound, and to compare the methods by and by knowing the echt weight of the baby after birth.MATERIALS AND METHODSIt is a prospective observational study of 200 women at term pregnancy at Dhiraj General Hospital, Vadodara from 1st June 2010 to thirty-first May 2011. Patients within 15 days from their Expected Date of Delivery were included in the study.Cases of MULTIPLE PREGNANCIES, OLIGO/POLYHYDRAMNIOS, MALPRESENTATIONS AND FIBROID OR ADNEXAL MASSES were excludedTHE METHODSJOHNSONS FORMULASYMPHYSIOFUNDAL HEIGHT X ABDOMINAL GIRTH.DAWNS FORMULAHADLOCKS FORMULA USING ULTRASOUND.JOHNSONS FORMULAW EIGHT IN GRAMS = (SYMPHYSIOFUNDAL HEIGHT x) X 155.Here symphysiofundal height is taken after correcting the dextrorotation, from the upper border of symphysis to the height of the fundus.station of the head was notedx = 12 when head was at or above the level of the ischial spinesx = 11 when head was below the level of ischial spines.AG X SFHWeight in grams = abdominal girth (AG) x symphysiofundal height (SFH) (AG X SFH)Abdominal girth was measured at the level of umbilicus and symphysiofundal height as described earlier.DAWNS FORMULAWEIGHT IN GRAMS =Longitudinal diameter of the uterus x (transverse diameter of the uterus)2 x 1.442HADLOCKS FORMULAAfter head circumference, abdominal circumference and femur space were measured in centimeters, the sonography machine calculated the fetal weight.Fetal weight estimated by the above four methods was compared with the actual weight of the baby after birth. A comparative analysis of the four methods was done.OBSERVATION AND RESULTSTABLE I W EIGHT WISE DISTRIBUTIONTABLE II AVERAGE ERROR IN CALCULATION OF FETAL WEIGHT IN VARIOUS GROUPSAverage error in all fetal weight groups except in 3500 gms was least with AG X SFH closely followed by Hadlocks ultrasound method.Average error in 3500 gms group was least with Johnsons formula.TABLE III NUMBER OF CASES UNDERESTIMATED AND OVERESTIMATED IN VARIOUS FORMULASNumber of over and under-estimations in all fetal weight groups was calculated.AG X SFH and Dawns formula had a tendency to underestimate. The other 2 methods overestimated.In 3500 gms group, all methods underestimated.TABLE IV MAXIMUM ERROR IN ALL FETAL WEIGHT GROUPSMost marked with Dawns and least with AG X SFH.By both these methods maximum error was in the 3001- 3500 gms group.By Johnsons formula, maximum error was in the TABLE V PERCENTAGE ERROR IN VARIOUS METHODSPercentage error was calculated usingx/y x 100x= error in gramsy= birth weight in gramsAs seen in the table, 85.5% cases came within 15% of actual birth weight by both Hadlocks and AG X SFH methods.As compared to only 50% and 63.5% by Dawns and Johnsons formula, respectively.TABLE VI STANDARD DEVIATION OF PREDICTION ERRORThe meter deviation of prediction error was least with Hadlocks formula, closely followed by AG X SFH.It is much higher with Dawns and Johnsons formulae.The dissonance between the four methods was statistically different. p value DISCUSSIONBirth weight is a key variable affecting fetal and neonatal morbidity, particu- larly in preterm and small-for-dates babies. In addition, it is of value in the management of breech presentations, diabetes mellitus, trial of labour, macrosomic fetuses and multiple births.Clinicians estimates of birth weight in term pregnancy were as accurate as routine ultrasound estimation in the week before delivery. Furthermore, parous womens estimates of birth weight were more accurate than either clinical or ultrasound estimation.There have been differing results about the accuracy of the va rious methods of estimating fetal weight.This study showed that AG X SFH was the best indicator among all of the other methods assessed followed by Hadlocks formula by ultrasonographic method.Other studies have reported limited accuracy of ultrasound EFW at term, particularly in macrosomic fetuses but over all accuracy of this formula is same for all infants.Equipped with information about the fetal weight the obstetrician managing labour is able to pursue sound obstetric management, reducing perinatal morbidity and mortality.Symphysiofundal height is one of the important clinical parameters taken for fetal weight estimation by AG X SFH, Johnsons formula, Dawns formula.According to my study, Hadlocks ultrasonographic method was the virtually accurate for estimating fetal weight.Of the three clinical methods, AG X SFH has better predictable results than the other 2 methods.AG X SFH, a clinical formula can be of great value in a ontogenesis country like ours where ultrasound is not a vailable at many health care delivery centres.It is easy and simple, can be used even by midwives. With less errors AG X SFH is easier to apply by paramedical workers for the evaluation of fetal weight even in the rural setup as like our area of this study. By this study the results are suggesting that Hadlocks formula has least standard deviation but it requires ultrasonographic evaluation. So after it, AG X SFH is the second most formula for estimation of featl weight which is clinically applicable and most reliable method in the absence of sonologic setup.CONCLUSIONFundal height assessment is an inexpensive method for display for fetal growth restriction.1 Clinicians are biased in their fundal height measurements by knowledge of gestational age and use of a marked metre tape. This tendency increases with higher patient BMI and with less provider experience.2 While we have yet to establish reliable tests to predict which pregnancies are at risk of developing IUGR, surveillance o f fetal growth in the third trimester of pregnancy continues to be the mainstay for the assessment of fetal well-being. Such surveillance is done by unfluctuating fundal height assessment, ultrasound biometry or a combination of both methods.3 Relative growth of the SF height seems to be independent of fetal sex, maternal fleshiness and parity.4 There is disagreement in SFH measurement between observers regarding the ability to separate small fundal heights from those that are not small (Bailey 1989). This becomes an issue especially in a clinical setting where the pregnant woman sees more than one clinician during the course of her pregnancy. Despite this, SFH measurement continues to be used in many countries on a large scale simply because of its low cost, ease of use, and need for very little training.5 Ultrasound evaluation of fetal growth, behavior, and measurement of impedance to furrow flow in fetal arterial and venous vessels form the cornerstone of evaluation of fetal c ondition and decision making.6REFERENCES1).Morse K, Williams A, Gardosi J (December 2009). Fetal growth screening by fundal height measurment.2).Jelks A, Cifuentes R, Ross MG (October 2007) Clinician bias in fundal height measurement.3).Gardosi Francis 1999, Morse et al 2009. Standardised protocol for measurment of symphysio fundal height4).Bergman E, Axelsson O, Kieler H, Sonesson C, Petzold M. Relative growth for estimation of intrauterine growth retardation. . Submitted. 2010.5).Robert Peter J, Ho J, Valliapan J, Sivasangari S. Symphysial fundal measurement (SFH) in pregnancy for detecting abnormal fetal growth (Protocol). The Cochrane Library. 2009(Issue 4).6).Resnik R. Intrauterine growth restriction. Obstet Gynecol. 2002 March.