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The Perinatal Umbilical Cord Project

The possible morbidity associated with umbilical cord complications ranges from neurological damage to isolated organ injury, such as the bowel and kidney.(15,16) Indirect morbidity may be associated with meconium, premature labour and unrecognised fetal heart failure secondary to cord anomalies. In spite of numerous publications since the 1900s, no prospective well-defined study has been conducted to investigate umbilical cord complications. To initiate such as large study, a pilot observational review was undertaken: the Perinatal Umbilical Cord Project (PUCP), for which local ethics committee approval was obtained.(17-19)

In a community of low-risk suburban mothers, 4948 deliveries were retrospectively reviewed for umbilical cord complications; 14 were documented at delivery, with the possiblity of more being unrecognised. All cases were stillborn and suggested a mortality rate of 2/1000 live births associated with such complications. Using this rate as a reference point, a goal of 1000 deliveries was established for the project.

Objective

The objective of the study was to conduct a prospective observational study, in a low-risk population (cohort), to determine the effect of umbilical cord complications on pregnancy.

Method

All patients accepted for management were informed of the PUCP. Preliminary observations suggested the ultrasound was accurate in identifying umbilical cord complications antenatally and later publications have confirmed this view.(20-24) Fetal monitoring is known to identify accurately fetal heart rate decelerations due to umbilical cord compression.(25,26)

In our study, 1250 pregnancies were accepted for management and 1064 deliveries occurred between 1989 and 1999. Routine screening tests were performed.

Antenatal ultrasound screening consisted of a 10-12 week vaginal ultrasound to confirm intrauterine pregnancy and pregnancy number. Abdominal scans at 20 weeks, 24 weeks, 28 weeks, and 30 weeks documented the presence of absence of umbilical cord complications and continued as indicated with subsequent antenatal visits. Placental lie and placental umbilical cord insertion were noted.

Fetal heart rate monitoring was undertaken for five minutes at each antenatal visit, starting at 20 weeks. Prolonged non-stress tests were used when appropriate. Labour occurred spontaneously or by induction at term. Repeat caesarean section was perfomed one week prior to the due date. Patients were managed according to traditional obstetrical principles. Patients with identified umbilical cord complications were managed routinely and interventions were undertaken for obstetric indications and not according to ultrasound findings. All patients were informed of umbilical cord complications when these were documented. Fetal activity awareness was emphasised and follow-up of any complaints was immediate.

A total of 1064 deliveries occurred with an overall caesarean section rate of approximately 25%. This rate was average for our community standard of practice. No litigation was experienced and patients appreciated knowing the detail of their ultrasound examinations. Patients were helpful in monitoring identified cases of umbilical cord complications.

One case of Down syndrome, one duodenal atresia, one cleft lip, two polycystic kidneys and one heart defect (tetralogy of Fallot) were identified. Table 26.2 reviews the umbilical cord complications encountered atenatally and at delivery and Table 26.3 reviews the outcomes observed after delivery that may be associated with umbilical cord complications.

Duration and unravelling of nuchal cords has been discussed elsewhere.(27) Of the 184 fetuses identified with entangled nuchal cords, 47 became unravelled and were not present prior to delivery. This observation raises the question of antenatal injury without witnessing and aetiology. The difference in rate between nuchal loops and nuchal cords was approximately 50%. This observation may explain the difficulty of previous studies to delineate couse and effect. Also, a trend was noted in a few patients with repeat pregnancies over ten years with a tendency to repeat entanglement. Our experience summarised here is that one can expect to encounter a ptentially harmful umbilical cord complication in at least 1/100 pregnancies managed to delivery. Ultrasound is helpful in identifying these umbilical cord complications antenatally. What remains to be determined by a larger study is the potential of identifying umbilical cord complications as an obstetric risk factor, for example at 36 weeks of gestation, and thus improve perinatal outcome.

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