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OB16 Obstetrics
Obstetrical Complications
Toronto Notes 2019
Preterm labour is the most common cause of neonatal mortality in the US
Positive fetal fibronectin in cervicovaginal fluid (>50 ng/mL) at 24 wk gestation predicted spontaneous PTL at <34 wk with sensitivity of 23%, specificity of 97%, PPV of 25%, NPV of 96%
Cerclage for Short Cervix on Ultrasonography in Women With Singleton Gestations and Previous Preterm Birth
Obstet Gynecol 2011;117:663-671
Purpose: To determine if cerclage prevents preterm birth (<35 wk gestation) and perinatal mortality and morbidity among women with previous spontaneous preterm birth, asymptomatic singleton gestation, and short cervical length (<25 mm before 24 wk gestation) on transvaginal ultrasonography. Methods: Meta-analysis of randomized trials identified using searches on MEDLINE, PUBMED, EMBASE, and the Cochrane Library.
Results: 5 trials included. Preterm birth was significantly lower among women receiving cerclage vs. those not receiving (RR = 0.70, 95%
Cl 0.55-0.89). Cerclage also significantly reduced preterm birth before 24, 28, 32, and 37 wk gestation. Perinatal mortality and morbidity were significantly lower in the cerclage group (RR = 0.64, 95% CI 0.45-0.91).
Conclusions: Cerclage significantly prevents preterm birth and perinatal mortality and morbidity in this specific group of women.
Obstetrical Complications
Preterm Labour
Definition
• labourbetween20and37wkgestation
Etiology
• idiopathic(mostcommon)
• maternal:infection(recurrentpyelonephritis,untreatedbacteriuria,chorioamnionitis),HTN,DM,
chronic illness, mechanical factors (previous obstetric, gynecological, and abdominal surgeries); socio-
environmental (poor nutrition, smoking, drugs, alcohol, stress), pre-eclampsia
• maternal-fetal:PPROM(common),polyhydramnios,placentaprevia,placentalabruption,orplacental
insufficiency
• fetal:multiplegestation,congenitalabnormalities,fetalhydrops
• uterine:excessiveenlargement(hydramnios,multiplegestation),malformations(intracavitary
leiomyomas, septate uterus, mullerian duct abnormalities)
Epidemiology
• pretermlabourcomplicatesabout10%ofpregnancies
Risk Factors
• priorhistoryofspontaneousPTListhemostimportantriskfactor
• prior history of large or multiple cervical excisions (cone biopsy) or mechanical dilatation (D&C)
• cervical length: measured by transvaginal U/S (cervical length >30 mm has high negative predictive
value for PTL before 34 wk)
• identificationofbacterialvaginosisandureaplasmaurealyticuminfections
■ routine screening not supported by current data, but it is reasonable to screen high-risk women • familyhistoryofpretermbirth
• smoking
• latematernalage
• multiple gestation
Prevention of Preterm Labour
A. Cervical Cerclage
• definition:placementofcervicalsuturesattheleveloftheinternalos,usuallyattheendofthefirst trimester or in the second trimester and removed in the third trimester
• indications: cervical incompetence (i.e. cervical dilation and effacement in the absence of increased uterine contractility)
• diagnosisofcervicalincompetence
■ obstetrical Hx: silent cervical dilation, recurrent 2nd trimester losses, cervical procedures such as
loop excisions
■ ability of cervix to hold an inflated Foley catheter during a hysterosonogram
■ transvaginal U/S of cervical length is recommended only for high-risk pregnancies and only before
30 weeks GA
• provenbenefitinthepreventionofPTLinwomenwithprimarystructuralabnormalityofthecervix
(e.g. conization of the cervix, connective tissue disorders)
B. Progesterone
• progesteronethoughttomaintainuterinequiescence,howeverexactmechanismofactionisunclear • IfpreviousPTL:17-alphahydroxyprogesterone250mgIMweeklyfrom16+0to36weeksGA
• If short cervix: 200 mg daily vaginally from time of diagnosis to 36 weeks GA
• Superior to cerclage in preventing preterm labour of singletons not due to cervical incompetence
C. Lifestyle Modification
• Smoking cessation, reduce substance use, treat GU infections (including asymptomatic UTIs), patient education regarding risk factors
Predicting PTL
• fetalfibronectin:aglycoproteininamnioticfluidandplacentaltissue ■ positive if >50 ng/mL; NPV > PPV
■ done if 1 or more signs of preterm labour (regular contractions >6/hr, pelvic pressure, low
abdominal pain and/or cramps, low backache)
■ done only if: 24-34 weeks, intact membranes, <3 cm dilated, established fetal well being
■ contraindicated as well if: cerclage, active vaginal bleeding, vaginal exam or sex in last 24 hours
■ if negative not likely to deliver in 7-14 days (>95% accuracy), if positive increased risk of delivery,
may need admission/transfer to centre they can delivery ± tocolysis and/or corticosteroids
Clinical Features
• regularcontractions(2in10min,>6/h)
• cervix>1cmdilated,>80%effaced,orlength<2.5cm