Cephalopelvic disproportion (CPD) exists when the capacity of the

pelvis The pelvis (: pelves or pelvises) is the lower part of an Anatomy, anatomical Trunk (anatomy), trunk, between the human abdomen, abdomen and the thighs (sometimes also called pelvic region), together with its embedded skeleton (sometimes also c ...

is inadequate to allow the

fetus A fetus or foetus (; : fetuses, foetuses, rarely feti or foeti) is the unborn offspring of a viviparous animal that develops from an embryo. Following the embryonic development, embryonic stage, the fetal stage of development takes place. Pren ...

to negotiate the

birth canal In mammals and other animals, the vagina (: vaginas or vaginae) is the elastic, muscular reproductive organ of the female genital tract. In humans, it extends from the vulval vestibule to the cervix (neck of the uterus). The vaginal int ...

. 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, scientific nomenclature: rachitis (from Greek , meaning 'in or of the spine'), is a condition that results in weak or soft bones in children and may have either dietary deficiency or genetic causes. Symptoms include bowed legs, stun ...

or a pelvic

fracture Fracture is the appearance of a crack or complete separation of an object or material into two or more pieces under the action of stress (mechanics), stress. The fracture of a solid usually occurs due to the development of certain displacemen ...

, and lead to CPD. Transverse diagonal measurement has been proposed as a predictive method.

Signs and symptoms

1. Prolonged Labor: Labor that does not progress as expected, particularly during the active phase. 2. Failure to Progress: Lack of dilation or descent of the baby despite strong contractions. 3. Severe Pain: Intense pain that is disproportionate to normal labor pain. 4. Fetal Distress: Signs like abnormal heart rate patterns detected via fetal monitoring. 5. Maternal Exhaustion: Extreme fatigue in the mother due to prolonged labor. 6. High Station: The baby’s head remains high in the pelvis and doesn’t descend despite strong contractions. Diagnosis of CPD usually occurs during labor, often requiring medical interventions such as a cesarean section (C-section) to ensure the safety of both mother and baby.

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 hyperglycemia, high blood sugar levels during pregnancy. Gestational diabetes generally results in few symptoms. Obesity increases the rate of pre-eclampsia, cesarea ...

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; 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 human pelvis, 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 ...

may identify cephalo-pelvic disproportion. However, a woman's pelvis loosens up before birth (with the help of hormones). A

Cochrane review Cochrane is a British international charitable organisation formed to synthesize medical research findings to facilitate evidence-based choices about health interventions involving health professionals, patients and policy makers. It includes ...

in 2017 found that there was too little evidence to show whether pelvimetry is beneficial and safe when the baby is in

cephalic presentation In obstetrics, a cephalic presentation or head presentation or head-first presentation is a situation at childbirth where the fetus is in a presentation (obstetrics), longitudinal lie and the Human head, head enters the pelvis first; the most ...

. 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.

References

External links