The technique and significance of amnioscopy

Use of maternal plasma level of zinc-coproporphyrin in the prediction of intrauterine passage of meconium: a pilot study

OBJECTIVE

To evaluate the usefulness of maternal plasma zinc-coproporphyrin (ZCP) level as a marker for intrauterine passage of meconium.

METHODS

A pilot study consisting of 10 pregnancies with meconium-stained amniotic fluid and 10 pregnancies with clear amniotic fluid was used. The corresponding plasma and amniotic fluid levels of ZCP were measured using spectrofluorometry. ZCP levels in plasma and amniotic fluid were compared between the two groups and the relation between plasma and amniotic fluid ZCP levels in the clear and meconium-stained groups was assessed using Spearman rank-order correlation.

RESULTS

Mean amniotic fluid ZCP was significantly higher in the meconium-stained amniotic fluid as compared to the clear amniotic fluid group. Although mean plasma ZCP levels were higher in the meconium-stained amniotic fluid group, this difference was not statistically significant. There was no significant correlation between plasma ZCP levels and amniotic fluid ZCP, but we could categorize patients according to plasma ZCP levels into four categories with different risks for having meconium-stained amniotic fluid.

CONCLUSIONS

Plasma ZCP might be a promising test for prediction of intrauterine passage of meconium in high-risk patients if confirmed by larger studies. The implications of this prediction on management remain unknown.

The value of amnioscopy in surveillance of postdate pregnancy

The accuracy and reliability of amnioscopy in detecting the presence of meconium in amniotic fluid and in predicting fetal distress were evaluated in 289 postdate pregnancies. Meconium-stained amniotic fluid tended to be associated with complications of pregnancy such as ABO incompatibility (p less than 0.05), the need for operative delivery (p less than 0.02), and fetal distress at birth (p less than 0.05). Amnioscopy failed to detect the presence of meconium antenatally in most cases (57%), and positive amnioscopy for meconium was unrelated to the incidence of fetal distress. When meconium was present, induction of labour was ineffective in reducing the incidence of fetal distress. Amnioscopy is not recommended for the monitoring of postdate pregnancies.

Recognition of meconium staining of the liquor aminii at amnioscopy

The results of a prospective investigation into the reliability of amnioscopy in the detection of meconium staining of the liquor amnii is presented. Under the conditions which prevail in most obstetric units, amnioscopy was found to be an unreliable method of detecting meconium staining of the liquor amnii. False-positive findings are infrequent but false-negative findings are common.