Indirect prediction of fetal lung maturity. Value of ultrasonographic colonic and placental grading.

OBJECTIVE: To correlate fetal morphometrics with studies of fetal lung maturity. STUDY DESIGN: One hundred six patients undergoing amniocentesis for fetal lung maturity studies were examined prospectively. Eighty-four patients were normal (79%), and 22 were diabetic (21%). Fetal morphometrics were obtained prior to amniocentesis. The fetal colon and placenta were graded. Discriminant analysis was used to identify variables that were predictive of a mature lecithin/sphingomyelin ratio and the presence of phosphatidylglycerol (PG). All patients delivered within 48 hours of amniocentesis. RESULTS: In the normal group, 28 (33%) fetuses had a grade 3 colon, which was 68% sensitive and 98% specific for a mature amniocentesis. A grade 3 colon was the single best predictor of a mature amniocentesis (P < .001). Twenty-five (29%) fetuses had a grade 3 placenta, which was 64% sensitive and 96% specific for a mature amniocentesis (P < .005). Diabetes did not influence colonic grading since a grade 3 colon was present in seven (32%) patients (47% sensitivity and 100% specificity for PG) (P < .02). Interexaminer and intraexaminer variability for the study was excellent, kappa = 1.0 (P < .001). CONCLUSION: Colonic and placental stage 3 grading are reliable and reproducible ultrasonographic scales that can help predict the findings of fetal lung maturity studies.

Porphyria cutanea tarda and pregnancy.

Porphyria cutanea tarda is the most common disorder of porphyrin metabolism in Europe and North America. The disorder is characterized by specific cutaneous lesions, associated systemic findings, and excessive accumulation and excretion of uroporphyrin and coproporphyrins. Reports of this condition associated with pregnancy are scarce in the literature. In this review, we present the case of a patient with porphyria cutanea tarda to illustrate the natural progression and complications of the disorder during pregnancy. Based in this report and a review of the published cases, pregnancy may exacerbate the cutaneous lesions of porphyria cutanea tarda during the first trimester. The incidence of diabetes, antinuclear antibodies, and hepatitis B and C are increased among them, making glucose tolerance and antibody testing mandatory. Newborns should be tested for the disorder during the neonatal period. Genetic counseling is advisable as well as teaching avoidance of provocative factors in affected children.

Limiting multiple pregnancy in in vitro fertilization/embryo transfer (IVF-ET) cycles.

PURPOSE: Our purpose was to assess how the number of embryos transferred can be adjusted to limit multiple gestations. METHODS: A retrospective analysis of 535 consecutive embryo transfers for the years 1991-1993 was conducted. RESULTS: Fewer than three embryos were associated with a low pregnancy rate. Pregnancy rates were highest in women less than 35 when four or more embryos were transferred. With four or more embryos, multiple gestation pregnancy correlated with the number of high-quality embryos transferred. The risk of triplets and quadruplets was greatest for women less than 40. CONCLUSIONS: Multiple-embryo transfer carries a risk of plural gestation. The risk of multiple pregnancy cannot be eliminated without decreasing the pregnancy rate. The risk of high-order multiple pregnancy was best correlated with the number of good-quality embryos transferred. While all are at risk, patients younger than 40 were at highest risk.

Vacuum sources in obstetrics.

OBJECTIVE: To characterize the performance of vacuum equipment used in operative vaginal deliveries. STUDY METHOD: We measured wall suction in eight Cleveland area labor-and-delivery units. Additionally, we tested samples of hand-operated and electric vacuum pumps. For each apparatus we recorded vacuum in millimeters of mercury using a calibrated, diaphragm-type gauge. We calculated mean maximal vacuum. Work required to produce 500 mm Hg of vacuum was determined for the hand-operated pumps. At increments of vacuum, we compared the vacuum displayed by the gauge head included with the device to our standard. RESULTS: Mean wall suction was 494 mm Hg (range, 248-655). As compared to the Mity-vac, the CMI hand-operated pump needed significantly more work to generate 500 mm Hg of vacuum. Electric pumps produced a reliable and consistent vacuum. Gauges included with the pump had an average error of 4% over 400-600 mm Hg. CONCLUSION: Wall suction was an unreliable source of vacuum. The two hand-operated pumps tested required significantly different amounts of work to achieve an adequate vacuum. Addition of a fluid trap does not affect the vacuum, and head gauges supplied with vacuum pumps are accurate.

The effect of artificial caput on performance of vacuum extractors.

OBJECTIVE: To isolate and describe the effect of chignon formation (vacuum-induced caput) on the performance of six vacuum extractors. METHODS: Six vacuum extractors were examined in the laboratory: the 6-cm Malmstrom, Mityvac, M-Type, Silc, Silastic, and Tender-Touch. The devices were tested in two model systems that duplicated the fetal scalp with and without chignon. A fetal cephalic model mimicked the head without chignon. The second model used the hind quarters of anesthetized dogs. Chignon was formed by slowly increasing vacuum until the target vacuum was reached. At increments of vacuum, traction was applied in the axis of the cup and maximal tractive force (pop-off) was measured. RESULTS: A statistically unique regression line described each device. There was no significant difference in the regression lines for the Malmstrom and M-Type cups with or without chignon. At equal vacuum, there was a significant decrease (P < .05) in maximal tractive force with chignon formation in the bell-shaped cups. CONCLUSIONS: There is a demonstrable deterioration in the performance of bell-shaped cups with the formation of chignon. These data suggest that when using a bell-shaped extractor, efforts should be directed toward minimizing chignon formation by applying vacuum only with traction.

Effect of angular traction on the performance of modern vacuum extractors.

OBJECTIVE: Our objective was to describe the effect of off-axis traction on the performance of modern vacuum extractors. STUDY DESIGN: Eight vacuum extractors were examined in the laboratory with a force indicator and fetal cephalic model. Devices evaluated included the 6 cm Malmstrom, Mity-Vac, M-Type, O'Neil, Posterior, Silc, Tender-Touch, and silicone elastomer. Maximal tractive force (pop-off) was measured for each device at 10-degrees increments from the vertical. RESULTS: Multivariate regression analysis described the best model as follows: Maximal tractive force = Constant + Angle + Vacuum (p < 0.05). The partial regression coefficients for angle were negative in all devices except the Posterior cup. At increasing angles of off-axis traction, maximal tractive force decreased in the following order: Silc, silicone elastomer, Tender-Touch, M-Type, Mity-Vac, O'Neill, Malmstrom, and Posterior. CONCLUSIONS: Application of oblique traction resulted in a linear decline in maximal tractive force. An understanding of in vitro performance may allow tailoring of cup selection to the clinical situation.

Laboratory comparison of modern vacuum extractors.

The Malmström, Soft Cup, and Mity-Vac vacuum extractors were compared in the laboratory using a tensile strength tester and a fetal cephalic model. In the test system, a linear relationship emerged between applied vacuum and maximal tractive force for all of the vacuum extractors. At their recommended working pressures, they allowed a maximum of 18-20 kg of tractive force to assist in a delivery. Calculation of the distribution of this force per unit area would appear to favor the Soft Cup. At high vacuums, all showed large amounts of tractive force and high forces per unit area. The data clearly demonstrate that high vacuum would have potentially adverse effects on the fetus and thus should be avoided.

Adnexal surgery in pregnancy.

Adnexal pathology is a rare event in pregnancy, occurring once in 556 deliveries in this study period, during which 23 patients underwent surgery for it. Eleven patients in the first two trimesters received perioperative prophylactic progesterone without a pregnancy loss. Two of three patients beyond 20 weeks required tocolytic therapy for apparent premature labor. Dermoid cysts and torsion of a corpus luteum cyst were the most common pathologic findings. The type of incision employed was based on uterine size and expected location of the adnexal pathology. It appears that the risk to the pregnant patient undergoing adnexal surgery can be minimized with judicious timing of the operation, preoperative incision planning and modern anesthetic techniques. The use of prophylactic progesterone is unproven, and further studies of this therapeutic modality should be undertaken.

A pilot community-based screening program for gestational diabetes.

A pilot community-based screening program for gestational diabetes has been in operation in Cleveland, Ohio, since April 1, 1977. A socioeconomic and racially heterogeneous group of pregnant women are being routinely tested at approximately 24-28 wk of gestation by a capillary whole blood glucose determination, 2-h after a 75-g oral challenge. The results of the first 2225 screenings are analyzed in terms of the variables of maternal race, age, and stage of gestation. The overall incidence of positive screenings (greater than or equal to 120 mg/dl) is shown to be 11.5%, with significantly more positive tests among the whites than the nonwhites. Follow-up oral glucose tolerance testing results in an overall detection rate for abnormal carbohydrate metabolism of 3.1%. The data suggest that a 2-h screening procedure is more efficient than a 1-h procedure in that fewer confirmatory glucose tolerance tests need to be performed in order to yield this rate of detection. It may soon be feasible to introduce such a program on a wider community basis in concert with regionalized perinatal care.