Dystocia - Diagnosis and Medical Management Flashcards
dystocia
inability to deliver neonates through the birth canal from the uterus
etiologies can be maternal, fetal, or combination of both
maternal etiologies of dystocia
inertia
uterine abnormalities
birth canal abnormalities
uterine inertia
uterus doesn’t contract properly during labor
can be primary or secondary to fatigue, stress, large litters, obesity, etc
uterine abnormalities that cause dystocia
herniation
torsion
rupture
excessive fluid
accumulation
lack of allantoic fluid
birth canal abnormalities
narrow or steep pelvic canal or vestibulo-vaginal abnormalities
fetal etiologies of dystocia
fetus spine should be aligned with the spine of the damn
what are signs that dystocia is occurring
- failure to initiate labor (stage I)
- failure to proceed to stage II
- failure to deliver all fetuses in a timely manner
- fetal or maternal distress
- copious vaginal discharge
- uteroverdin without immediate delivery
- irreversible history of dystcoia
uteroverdin
green vaginal discharge; indicates separation of the placenta from the endometrium
indicates that the fetus is in the birth canal without placental blood supply - must deliver ASAP
how to diagnose dystocia
- ensure correct due date - is she supposed to be in labor at this time?
- minimum database - check BUN, BG, Ca, ketonuria
- radiographs - confirm pregnancy, count fetusses, evaluate size compared to birth canal
- US or fetal doppler - evaluate fetal HR
- tocodynamometry - is the uterus contracting appropriately
gestational length in dogs
56-58 days from day 1 of diestrus
64-66 days from initial progesterone rise (LH surge)
58-72 days from first breeding
gestational length in cats
65-66 days from coitus that caused the LH surge
52-74 days from first to last breeding
what is a reverse progesterone test
measure progesterone on the expected day of whelping/queening
if <2.0 –> should be at term
how to do ultrasound gestational aging
use the biparietal (head) diameter of the fetuses
can be used after day 40 of gestation
dog GA = (diameter x 15) + 20
- due date is 64 - GA
cat GA = (diameter x 25) + 3
- due date is 64 - GA
how should full term fetuses appear on radiographs
dentition should be mineralized
what fetal heart rate indicates fetal stress
bradycardia (<180 bpm)
stage 1 labor
duration: 12-24 hours
increasing frequency and strength of uterine contractions and cervical dilation
NO abdominal effort/pushing
behavioral changes: restlessness, reclusive, nesting, refusal to eat, panting
clear and watery vaginal discharge
stage 2 labor
duration: total 1-24 hours (maximum 1 hour to first puppy; should not exceed 1 hour between puppies)
clear to bloody vulvar discharge
- green is BAD (uteroverdin)
behavior: same as stage 1 between deliveries, loss of appetite, panting
stage 3 labor
duration: within 24 hours
delivery of the placenta - will be delivered either with the neonate still attached OR after the neonate delivery
ensure all placentas get delivered (1 per puppy) - can give small dose of oxytocin to ensure delivery of all placentas
how to assess dystocia
tocodynamometry
fetal ultrasound
want to know what the uterus is doing and how the fetuses are doing
tocodynamometry
permits evaluation of uterine activity (contraction) before and during labor
tocodynamometer characteristics of stage 2 labor
0-12 contractions per hour
15-40 mmHg per contraction
duration: 2-5 minutes per contraction
fetal ultrasound
permits evaluation for fetal distress by visually assessing heart rate
if <150-180: fetal stress
if <130: poor survival unless delivered in 1-2 hours
if <100: immediate intervention required
normal fetal heart rate
180-210 bpm
how to treat uterine inertia
most often SECONDARY uterine inertia - labor is initiated and then ceases due to fatigue during parturition
TX: 10% Ca gluconate SQ
- must do radiographs to rule out obstructive dystocia
- must ensure fetal HRs are adequate before and after admin
- if NO neonate within 15-30 minutes –> add in oxytocin
Ca gluconate
improves the STRENGTH of myometrial contractions
ALWAYS given first
oxytocin
improves the frequency of myometrial contractions
more risky - often overdosed so give in mini doses
surgical management of dystocia
Cesarean section
used when medical therapy fails or is contraindicated
contraindications for medical management of dystocia
- fetal distress despite medical treatment
- obstruction
- maternal distress, hemorrhage, shock
- refractory inertia
- aberrant or obstructive tocodynamometry pattern
what are the 3 stages of labor
S1: increasing uterine contraction frequency and strength; should progress to stage 2 within 9 hours
S2: uterine contractions WITH abdominal contractions; should result in delivery within 1 hour (all puppies within 9 hours)
S3: delivery of the placenta (hours to days after neonate)
what are the 3 broad categories of dystocia
- maternal
- fetal
- combination of maternal and fetal (most common)
what are the two drugs used to medically treat dystocia
Ca Gluconate - improve STRENGTH of contractions
Oxytocin - improve FREQUENCY of contractions
ALWAYS check fetal heart rate after giving drugs
indications for C section
- fetal-maternal mismatch in size
- collapse or decompensation of the dam despite treatment
what are complications associated with singletons or small litter sizes
small litter size or singleton results in NO crowding stress –> no cortisol release from the fetuses –> no signal to initiate labor –> fetuses outgrow the fetal blood supply
advise elective C section for these cases
