A study to investigate the relationship between obstetric brachial plexus palsies and cephalopelvic disproporation (including fetal macrosomia)

Abstract

In view of the lifelong impact of Obstetrical Brachial Plexus Palsies (OBPP), prevention of OBPP would be of great significance. Despite contemporary advances in antenatal planning and assessment, OBPP remains an unfortunate consequence after difficult childbirth. Permanent brachial plexus palsy is a leading cause of litigation related to birth trauma.

Objectives: To determine the incidence of Obstetrical Brachial Plexus Palsy (OBPP), Cephalopelvic Disproportion (CPD) and macrosomia in KwaZulu-Natal. As well as to investigate the relationship between OBPP and CPD, and the relationship between OBPP and macrosomia. The study also aimed to determine whether antenatal risk factors could identify those prone to OBPP.

Study design: This was a case control study that included all deliveries from 1997 to 2000 from four provincial hospitals (Addington, King Edward VIII, Prince Mshiyeni Memorial and RK Khan hospital). The outcome variable was OBPP. Results were analyzed using Statistical Program for Social Sciences (SPSS).

Results: A total of 60 infants of 76 352 deliveries sustained OBPP. The incidence of OBPP was found to be 0.72 per 1000 deliveries. The incidence of CPD was found to be 33.5 per 1000 deliveries and the incidence of macrosomia was found to be 16.7 per 1000 deliveries. Race, Maternal height> 150 cm, gravida >3, parity >4, history of a previous big baby, normal vaginal delivery, delivery by a midwife, difficult labour, inadequate or doubtful pelvic capacity, birth weight of >3700 g and gestation period> 34 weeks were significant risk factors. Logistic regression analysis showed that race, parity> 4, normal vaginal delivery and gestation period> 35 weeks were the variables most associated with OBPP. Using linear regression model was obtained for the calculation of predictive risk scores.

Conclusion: Using standard statistical formulae the probability of OBPP can be calculated in women with significant risk factors from the logistic regression formula. This would need to be validated and could provide a useful tool for screening for OBPP thus contributing to preventing this devastating complication of birth trauma. The risk assessment profile would contribute greatly to the prediction of OBPP and the subsequent prevention of this debilitating birth injury.