PRETERM LABOR OBSTETRICS MODULE Janet Gould, DO Case Presentation HPI: You are called to triage to see a 26 yo AAF G2 P0101 c/o pelvic pressure & a lower backache. States she is having menstrual-like cramping. Denies any vaginal bleeding or LOF. She is at 28 wks gest by dates & early U/S. OBHx: 1st child delivered by C/S @ 29 wks after tocolysis w/ MgSO4 & terbutaline had failed & fetus was found to be breech PMHx: Chlamydia infxn x 3; last episode in 1st trimester of current pregnancy Continue You are concerned this patient may be in preterm labor. What are her for preterm labor? Click on “answer” to see if you are correct. ANSWER The patient presented in the case has the following for preterm labor: 1. African American race 2. Prior h/o preterm labor 3. H/o chlamydial infxn during current pregnancy *Click the “info button” to view other risk factors for PTL. Maternal Factors Infection - Low socioeconomic status - Chorioamnionitis - Nonwhite race - BV - Maternal age <18 or >40 - STDs - Low prepregnancy wt - Smoking/Substance abuse Maternal Hx Uterine Factors - Previous h/o PT delivery - Multiple gest; polyhydraminos - H/o 2nd trimester Ab - Uterine anomalies Next You are in the triage room obtaining the pt’s complete hx & verifying her dates. The triage nurse appears to be in quite a hurry. She asks if you will need anything, as she quickly puts on the maternal & fetal monitors. You tell her: Yes, you will need to do a speculum exam. Yes, you just need to do a cervical exam. No, you just want to wait & see what’s on the monitor. : perform a speculum exam Why do a speculum exam? To check for fetal fibronectin. To check vaginal cultures. To do a GBS culture. To check for ROM. All of the above. There is one step you must do first that cannot be done after a digital exam. And you always want to be active in your management of a PTL pt. Waiting is not the appropriate answer. BACK You perform a speculum exam in order to obtain vaginal cultures, a GBS cx and fetal fibronectin. A sterile speculum exam is also necessary in order to check for ROM. NEXT You are partially correct. Actually, you want to check all of these tests. BACK So, you perform the sterile speculum exam & collect vaginal cx, GBS & FF. She clearly has not had ROM. Thus, you do a digital exam & find: 2cm/50%/-2. NEXT The nurse leaves the room. You then finish the PE. Click on the file folder to view the results of the exam. . Patient File Physical Exam VS: T:98.7 BP:110/76 P:78 R:12 PE: • Gen: anxious; AAO x 3; NAD • HEENT: wnl • Neck: (-) thyromegaly; (-) LAD • Lungs: CTA b/l; (-)w/r/r • Heart: Grade 2/6 SEM @ LLSB • Abd: gravid; non-tender; (-)rebound/guarding • Ext: (-) c/c/e • Neuro: CNII-XII intact; (-)focal deficits; 2+DTRs • VE: cervix: 2/50%/-2; no abnormal vag d/c fundus: 30cm presentation: breech NEXT You have completed the maternal exam. You now wish to assess fetal well-being. How would you do so? Answer : External Monitoring & U/S External monitoring is used to determine FHR pattern & ctx pattern U/S is used to determine gest age, presentation, placental location & fetal anomalies. Click on “results” to view the findings on external monitor & U/S. RESULTS Results External Monitoring FHR:160’s (+)accels (-)decels (+)LTV Toco: mild ctxs q 8-10min U/S (performed by OB resident on-call): gest age: 28 weeks size (+/- 2 wks) presentation: breech AFI: 15 Next 26 yo G2P1 @ 28 wks gest c/o pelvic pressure & ctxs Has previous h/o PTL Cervical exam: 2cm/50%/-2 Toco w/ mild ctx q 8-10 min. FHT w/ a reassuring pattern Fetal fibronectin RETURNS RESULT Fetal fibronectin result: What is Fetal Fibronectin? - Protein found in the fetal membrane, decidua & amniotic fluid. It functions as adhesive between embryo & uterus. - As the gestational sac implants, FF normally appears in cervicovaginal fluid, but the presence FF is rare after 24th week - After 24th wk, +FF may indicate detachment of fetal membrane from decidua - Important to memorize about FF test: excellent negative predictive value, i.e. if FF is negative, <1% of women will deliver in next week. NEXT You believe you have gathered all of the necessary information to diagnose PTL. To be certain, you search the internet for information on diagnosing PTL. Click Here Preterm Labor: Diagnosis Identify si/sx of PTL √ Pt between 20 and 36 wks √ Uterine ctxs @ 4 per 20 min or 8 per 60 min √ Ctxs accompanied by: - PROM - Dilation > 2 cm √ - Effacement > 50% √ - Or cervical change detected by serial exams NEXT Based upon the info. You have gathered on your patient, you are still unsure if you can dx. the pt with PTL. What other test can you do to help you in your PTL evaluation? Answer Transvaginal Ultrasound Cervical length may be a useful predictor of PTL, w/ shorter cervix predicting higher risk of PT delivery Given many variations of digital exams, it is thought transvaginal U/S allows an objective approach to the cervical exam The OB resident helps you to perform the transvaginal U/S - - the : 2.5 cm Next Preterm Labor Evaluation: Utility of Fetal Fibronectin & U/S If dx of PTL is uncertain, obtaining fetal fibronectin & transvaginal U/S is a reasonable strategy If FF (-) & cervical length > 3cm, pt can be sent home b/c likelihood of delivering in next week <1% NEXT Now, you are very concerned about the Possibility of PTL, especially due to her risk factors, freq ctxs, FF & cervical length. What management strategies should you be thinking about? Click on the “info button” to learn more about PTL management strategies. Preterm Labor: Management Therapeutic Goals: 1) inhibit/reduce strength & freq of ctxs, thus delaying time to delivery 2) optimize fetal status before PT delivery Consider , including: 1) Tocolytic therapy 2) Corticosteroids 3) Antibiotics 4) Transfer to tertiary care center NEXT After reviewing the management strategies, you consider starting tocolytics. Will tocolytics prevent preterm labor? If not, what are the benefits of using tocolytics? Click on the “info button” to find out more about tocolytic therapy. PTL Treatment: Tocolytics Tocolytics stop ctxs temporarily, but do not prevent preterm birth Used alone, they convey little or no benefit in neonatal outcome HOWEVER They are effective in delaying delivery for 24 - 48°, which is long enough for administration of steroids & transfer to tertiary care center Can have adverse health effects on women Contraindications : - nonreassuring FHT - eclampsia - fetal demise - chorioamnionitis - fetal maturity - maternal instability Next Which tocolytic will you use? What dose will you choose? You go to your palm pilot for some more info. regarding tocolytics. Click on the “palm pilot” to review tocolytics. Tocolytics * MgSO4 * Nifedipine - Ca2+ antagonist - Ca2+ channel blocker - 4g load IV, then 1-3g/hr - 20mg po, then 10-20mg q 6-8° - SE: resp & cardiac arrest - SE: maternal hypotension - Monitor DTRs & Mg levels - Monitor BP * Terbutaline * Indocin - ß2 activator - Prostaglandin inhibitor - 0.25- 0.5mg SC q 30min - 50mg load, then 25mg q6 ° - SE : ischemia, arrhythmias & - SE: maternal GI upset; oligo; pulm edema ductal constriction - Monitor cardiac rhythm, fluid/lytes - Not used after 32 wks Next You decide to use for tocolysis. You order 0.25mg SQ x 1 q 30min. NEXT Your patient has been in triage for 2 hours. She has received 2 doses of Terbutaline, but continues to contract every 5-10min. You re-examine her cervix & find: 3cm/50%/-2 NEXT Yikes !! You now confirm the dx. of PTL: - regular ctxs - cervical change You decide to transfer care of this preterm labor patient to OB , but they’re all in C/S!! What else can you do in the meantime to improve the newborn’s chance of survival? Answer PTL Treatment: Corticosteroids Steroids are the only tx that improves fetal survival when given 24-34 wks gestation. They are typically not used >34 wks, b/c perinatal outcomes are generally good. Studies have shown a decrease in intravent. hemorrhage, RDS & mortality w/ steroid tx. Optimal benefits begin 24hrs after tx & last for 7 days NEXT Based upon this info, your patient at 28 wks gest would benefit from steroid therapy. Typically, what steroids are used in the management of PTL? What are the appropriate doses? answer Corticosteroid Therapy Treatment regimens for PTL include : Betamethasone 12mg IM q 24° x 2 days OR Dexamethasone 6mg IM q 12° x 2 days Next You have diagnosed your patient @ 28 wks gest age with PTL. You started tocolytic therapy with terbutaline in order to delay delivery. This allows time to administer steroids to enhance fetal lung maturity. Now, what about antibiotics? Do we need them? Answer PTL Treatment: Antibiotics Infections play an etiologic role in PTL Pts in PTL are at high risk for neonatal GBS sepsis & should receive prophylactic antibx. Initiate at dx of PTL & continue until delivery Tx will prevent perinatal transmission This approach will not prevent PTL Continue Since your pt is <37 wks gest age, you want to start antibiotics for GBS prophylaxis. What antibxs are used for GBS prophylaxis? What are the appropriate doses? Answer GBS Prophylaxis PCN G 5 million U IV load, then 2.5 million U q 4 hrs until delivery Amp 2g IV load, then 1 g IV q 4 hrs until delivery If PCN allergic, Cleocin 900 mg IV q 8hrs until delivery, or E-mycin 500mg IV q 6 hrs until delivery Continue You’ve got the tocolytics, steroids & antibx on board. You’re at MUSC which has a NICU, thus there is no need to transfer care. If labor continues to progress, how will you deliver the baby, vaginally or via C/S? Answer Delivery Birth at a center with a NICU is one of the best predictors of neonatal survival In PTL, likely to have fetuses born breech - less likely to have traumatic & asphyxial injuries when delivered via C/S In PT vertex infants, C/S performed for same indications as in term infants - no evidence that delivery by C/S improves outcome Recall that the U/S showed the baby in a breech presentation. Thus, a C/S will be performed to deliver the baby. Click on summary to review PTL strategies. Summary Summary Preterm delivery accounts for substantial component of all neonatal M&M. Effective interventions to decrease spontaneous preterm delivery have not been discovered. Successful management includes: - preventing neonatal dz - use of corticosteroids for fetal maturation - when appropriate, GBS prophylaxis - reducing trauma & asphyxia during delivery - transferring to site that can perform expert resuscitation & provide intensive care Click to view References References Beckmann, Charles R. et al. Obstetrics and Gynecology. 4th edition. 2002; 304-311. Goldenberg, Robert L. The management of preterm labor. The American College of Obstetricians and Gynecologists. November 2002. Vol. 100, Number 5, Part 1; 1020-1037. Newton, Edward R. Preterm Labor. E-medicine. Sept. 15, 2005. Von Der Pool, Beverly A. Preterm Labor: Diagnosis and Treatment. Amer Family Physician. May 15, 1998. Weismiller, David G. Preterm Labor. Amer Family Physician. Feb. 1, 1999.
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