Algorithm for threatened PTL:
1 History
(a) Are the dates accurate?
Determinedthrough earlydocumentation with ultrasound or compelling inform- ation about the patient’s menstrual dating or time of conception.
(b) Previous history of PTL?
© On tocolytics now or in the past?
(d) Any history compatible with rupture of membranes in this pregnancy?
2 Transabdominal ultrasound
(a) Assess amniotic fluid volume.
(b) Obtain biometric estimation of gestational age (AUA).
© On occasion, look for epiphyseal centers ( DFE and PTE )
(d) Repeat the full fetal survey especially if done earlier in pregnancy.
If the history and/or ultrasound confirm the patient’s dates, then move to the next step.
3 Transvaginal ultrasound
(a) Do CL measurement
(1) If CL is greater than 3 cm, simply
observe patient and send her home
when contractions abate.
(2) If CL is 1.5–3 cm, send off fetal
fibronectin.
(3) If fibronectin is positive, admit as long as contractions persist.
(4) If fibronectin is negative, discharge.
(5) If CL is less than 1.5 cm, admit.