​Kembara Xtra - Medicine - Preterm Labour

​Kembara Xtra - Medicine - Preterm Labour 
Regular contractions occurring between 20 and 36 weeks and 6 days with either a cervical dilatation of less than 2 cm at presentation or a change in effacement.

Epidemiology 
In the US, preterm delivery is the main contributor to perinatal morbidity and mortality.
Incidence
Preterm labor occurred at least once in 15% to 20% of pregnancies.
Prevalence
Preterm births made for 10.23% of all births in the US in 2019. Preterm births are 50% more common in non-Hispanic black women than in Hispanic or white women.


Pathophysiology and Etiology 
Premature myometrial gap junction development and activation, abnormal placental implantation, systemic inflammation and infections (like UTI), and local inflammation and infections (like intra-amniotic infections).
Uterine anomalies, overdistension (due to repeated pregnancies or polyhydramnios), preterm premature membrane rupture, trauma, placental abruption, immunopathology (such as antiphospholipid antibodies), and placental ischemia disease (preeclampsia and fetal growth limitation), among other factors.
Genetics
familial propensity. There are several gene candidates that mediate different pathways, but causation and gene-environment interactions are not clearly understood.

Risk factors include previous preterm birth (the most significant risk factor), socioeconomic disadvantages, and black race, which raises concerns about chronic stress from structural racism.
Short interpregnancy interval (18 months) Prepregnancy weight 45 kg (100 lb), BMI 18.5 Substance abuse (e.g., cocaine, tobacco) Unintended pregnancy History of dilation and curettage Cervical insufficiency Short cervical length of 25 mm Abdominal surgery/trauma during pregnancy Uterine structural abnormalities, such as large fibroids or s


Prevention 

 Patient education is provided to all patients at risk at every visit in the second and third trimesters and on occasion in the last two trimesters.
On a standard fetal anatomical scan, the cervix should be visible at 18 0/7 and 22 6/7 for women who are carrying a singleton and have no prior history of spontaneous preterm births. Transvaginal ultrasounds should be performed for additional assessment if discovered to be shortened.
The advice is the same for women carrying multiple children and those who have already had medically induced preterm birth. During the second trimester, twin pregnancies are more likely to result in a shortened cervix, and recurrent preterm births are more likely among women who have previously had medically induced preterm birth.
For women who have previously experienced spontaneous preterm birth and singleton pregnancies, a screening transvaginal ultrasound should be performed at 16 0/7 weeks and then every two weeks until 24 0/7 weeks to measure the cervix length. During this stage, many regimens would repeat every one to four weeks.
Primary prevention includes the following: - Interval contraception to maximize pregnancy spacing - Smoking cessation - If a previous preterm delivery occurred, determine whether the underlying cause is likely to return and focus intervention on that condition.
- A shared choice approach should be used when offering vaginal or intramuscular progesterone to women who have a history of spontaneous preterm delivery and singleton pregnancy in order to prevent preterm birth.
Secondary prevention: It is advised to administer vaginal progesterone to women with cervixes less than 25 mm, whether or not they have a history of spontaneous preterm births in the past or singleton pregnancies. Most protocols prescribe 200 mg per day starting at diagnosis between 18 0/7 and 25 6/7 and continuing during 36 – 37 weeks.
- A cerclage should be taken into consideration for women who are carrying a singleton and have a history of spontaneous premature births with shortened cervix.
- For numerous gestations, there is inadequate data to support vaginal progesterone.
- Any patient whose physical examination reveals cervical insufficiency should be given consideration. - In any patient with a shortened cervix, a cervical pessary is not advised.
In tocolysis

Diagnosis 

Regular contractions and significant cervical changes (such dilatation or effacement) are typically combined to make a diagnosis. However, no single test can accurately identify or foretell real preterm labor. Physical findings and diagnostic tests are used to make the diagnosis, which is then interpreted in light of the patient's level of risk.

Discuss the risk variables throughout history.
Regular cramping or contractions of the uterus; dull, low backache; occasional lower abdomen discomfort; increased low pelvic pressure; a change in the discharge from the vagina; vaginal bleeding; and fluid leaking.

clinical assessment 
Sterile speculum examination for cultures, bimanual cervical examination, and evaluation of membrane rupture.
ALERT
When feasible, stay away from bimanual inspection if membrane rupture is suspected.

Differential Diagnosis: Adnexal Torsion, Appendicitis, Nephrolithiasis, Braxton-Hicks contractions/false labor, Round Ligament Pain, Lumbosacral Muscular Back Pain, UTI or Vaginal Infections

Initial test results from the laboratory and imaging
There are a few tests that can aid with risk stratification, but none of them can reliably predict preterm birth.
 Collect a fetal fibronectin (FFN) swab from the posterior vaginal fornix in symptomatic pregnant women between the ages of 22 and 34 weeks who have intact membranes and haven't had sex or bled recently. Before doing a digital cervical exam, FFN is required.
The patient has a somewhat higher risk of giving birth prematurely if the results are positive (50 ng/mL; positive predictive value [PPV] 13–30% for delivery within 2 weeks).
- If the results are bad, you might want to think twice about undergoing difficult or risky treatments because >97% of patients won't give birth within 14 days.
- In order to effectively manage the patient's acute condition, other data should be employed in addition to fetal fibronectin and a shortened cervix.
Urinalysis and urine culture; cultures for gonorrhea, chlamydia, and wet prep; vaginal introitus and rectal culture for group B Streptococcus, if indicated; pH and ferning test of vaginal fluid to assess for rupture of membranes; CBC with differential and Kleihauer-Betke test if abruption is suspected; and US to count the number of fetuses and determine their positions;

Tests in the Future & Special Considerations
After successful therapy, increasing alterations of the cervix on repeat inspection or US (in 1 to 2 weeks) may indicate need for hospitalization. Repeat FFN as indicated by symptoms. 
Other/Diagnostic Procedures
Consider amniocentesis at any preterm gestational age to check for intra-amniotic infection and keep an eye on your contractions using an external tocodynamometer.


Treatment of underlying risk factors is necessary for management; if IV tocolysis is required, hospitalization is also required.

Medication 
Although it may not considerably lengthen pregnancy, tocolysis may give time for measures like transfer to a tertiary care institution and the administration of corticosteroids.

Initial Line

If the mother is between 24 and 34 weeks' gestation and is at danger for giving birth within the next seven days, corticosteroids should be administered; if the mother is between 23 weeks and 23 weeks and six days, they should be taken into consideration.
- Neonatal respiratory distress, intraventricular hemorrhage, necrotizing enterocolitis, and total perinatal mortality are all reduced by corticosteroids.
- Dexamethasone 6 mg IM q12h for 4 doses or betamethasone 12 mg IM 2 doses 24 hours apart.
- In singletons born to nondiabetic moms during the late preterm period (34 + 0 to 36 + 6 weeks' gestation), steroids may lower the incidence of respiratory morbidities.
The administration of steroids may be taken into consideration as above if delivery is probable during this time.
Tocolysis should not be used.
Tocolysis should only be used in women who would benefit from a delay of 48 hours in the administration of corticosteroids because there is no proof that it would improve the outcomes for newborns. - Nifedipine: monitor blood pressure frequently to prevent hypotension, then take 10 to 20 mg every four to six hours for 48 hours (do not take this medication sublingually). The potential danger of neuromuscular inhibition makes concurrent use of magnesium sulfate undesirable.
- Indomethacin: 50–100 mg PO for the first dose, followed by 25–50 mg every 6–8 hours. Due to the danger of premature ductus arteriosus closure, oligohydramnios, and perhaps infant necrotizing enterocolitis, use for longer than 72 hours is not advised. If used for neuroprotection, it is best utilized in conjunction with magnesium.
- severe preeclampsia, bleeding, chorioamnionitis, advanced labor, intrauterine growth restriction, fetal distress, or fatal fetal anomalies are contraindications to tocolysis.
Magnesium sulfate is advised for expectant mothers before 32 weeks of pregnancy for neuroprotection as it lowers the risk of cerebral palsy. Antibiotics: antibiotics for group B Streptococcus prophylaxis if culture is necessary.


Second-line chemotherapy
It has not been demonstrated that magnesium sulfate IV infusion is superior to placebo in extending pregnancy past 48 hours. The negative effects are typically more severe than those caused by NSAIDs or calcium channel blockers. As a result, this agent needs to be used with caution.
Terbutaline administered intravenously. Change to a different tocolytic medication if contractions continue or your pulse is over 120 beats per minute. Terbutaline should not be administered PO or long-term SC due to reports of significant cardiovascular events and maternal fatalities.
pulmonary edema from crystalloid fluids and tocolytic drugs, particularly magnesium sulfate, are significant potential interactions. Antibiotics should not be used as tocolysis or to improve infant outcomes for preterm labor with intact membranes as they may be harmful. This is not the same as the advice for GBS and ruptured membranes.


Referral Consider transport to a tertiary care facility or hospital with a newborn ICU if delivery is unavoidable but not urgent. Think about speaking with a maternal-fetal medicine specialist.

Further Therapies 
There is a dearth of evidence to support the effectiveness of pelvic rest (i.e., no douching or intercourse).
Bed rest and hydration are not advised because they have not been proven to be successful in preventing premature birth.


Surgical Techniques 
If labor is advancing and there is a risk of malpresentation or fetal compromise, think about a cesarean delivery.
Consider cerclage (up to 24 weeks of pregnancy) if you have cervical insufficiency.


Admission

Preterm labor suspected or threatened; IV access; ongoing fetal and contraction monitoring; check for cervical dilation and effacement.
IV hydration • Fluid excess should be watched closely.

Regular use of maintenance tocolysis is unsuccessful in preventing repeat preterm labor or premature birth. Instead, follow-up patient monitoring should include weekly office visits with contraction monitoring, cervical checks, or cervical US if at high risk for recurrence.

Education of Patients 
When regular contractions linger longer than an hour, there is bleeding, more vaginal discharge or fluid, or decreased fetal activity, call your doctor or get to the hospital.

if the membranes are breached and an infection is not found, the prognosis is good. Delivery usually happens within 3 to 7 days.
20–50% of women who have intact membranes give birth prematurely.

Complications 
Tocolysis-resistant labor, pulmonary edema, and intraamniotic infection