Cephalopelvic disproportion exists when the capacity of the pelvis is inadequate to allow the fetus to negotiate the birth canal. This may be due to a small pelvis, a
nongynecoid pelvic formation, a large fetus, an unfavorable orientation of the fetus, or a combination of these factors. Certain medical conditions may distort pelvic bones, such as
rickets
Rickets is a condition that results in weak or soft bones in children, and is caused by either dietary deficiency or genetic causes. Symptoms include bowed legs, stunted growth, bone pain, large forehead, and trouble sleeping. Complications ma ...
or a pelvic
fracture, and lead to CPD.
Transverse diagonal measurement has been proposed as a predictive method.
Causes
A large fetus can be one cause of CPD. A large fetus can be caused by
gestational diabetes
Gestational diabetes is a condition in which a woman without diabetes develops high blood sugar levels during pregnancy. Gestational diabetes generally results in few symptoms; however, it increases the risk of pre-eclampsia, depression, and o ...
,
postterm pregnancy
Postterm pregnancy is when a woman has not yet delivered her baby after 42 weeks of gestation, two weeks beyond the typical 40-week duration of pregnancy. Postmature births carry risks for both the mother and the baby, including fetal malnutrition, ...
, genetic factors, and
multiparity.
The shape of the pelvis can also be a cause of CPD. The pelvis may be too small, or the shape of the pelvis may be malformed.
Shorter women are more likely to have CPD
as are adolescents.
Diagnosis
Diagnosis of CPD may be made when there is
failure to progress, but not all cases of prolonged labour are the result of CPD. Use of ultrasound to measure the size of the fetus in the womb is controversial, as these methods are often inaccurate and may lead to unnecessary
caesarian section
Caesarean section, also known as C-section or caesarean delivery, is the surgical procedure by which one or more babies are delivered through an incision in the mother's abdomen, often performed because vaginal delivery would put the baby or ...
; a trial of labour is often recommended even if size of the fetus is estimated to be large.
Theoretically,
pelvimetry
Pelvimetry is the measurement of the female pelvis. It can theoretically identify cephalo-pelvic disproportion, which is when the capacity of the pelvis is inadequate to allow the fetus to negotiate the birth canal. However, clinical evidence ind ...
may identify cephalo-pelvic disproportion. However, a woman's pelvis loosens up before birth (with the help of hormones). A
Cochrane review
Cochrane (previously known as the Cochrane Collaboration) is a British international charitable organisation formed to organise medical research findings to facilitate evidence-based choices about health interventions involving health profes ...
in 2017 found that there was too little evidence to show whether pelvimetry is beneficial and safe when the baby is in
cephalic presentation
A cephalic presentation or head presentation or head-first presentation is a situation at childbirth where the fetus is in a longitudinal lie and the head enters the pelvis first; the most common form of cephalic presentation is the vertex pre ...
.
A review in 2003 came to the conclusion that pelvimetry does not change the management of pregnant women, and recommended that all women should be allowed a trial of labor regardless of pelvimetry results.
It considered routine performance of pelvimetry to be a waste of time, a potential liability, and an unnecessary discomfort.
Treatment
In the case of a fetus being too large, some obstetricians recommend
induction of labour for earlier delivery. Diagnosis of CPD in active labour will usually result in a
Caesarian section.
See also
*
Trial of labour In obstetrics a trial of labour is the conduction of spontaneous labour in a moderate degree of cephalopelvic disproportion. It is performed under close observation by an obstetrician in order to assess a woman's chances of a successful vaginal bi ...
References
External links
Complications of labour and delivery
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