A doctor who examined 16-year-old Rita McDowell immediately after she was admitted to D.C. General Hospital on March 7, 1975, testified yesterday that McDowell was suffering from infection and shock as result of an incomplete abortion.

Dr. Winston H. Blake told a D.C. Superior Court jury that three hours later, McDowell's "condition had worsened considerably" and that "her prognosis for survival was extremely poor."

Early the next morning, McDowell died, four days after she was treated by Dr. Robert J. Sherman at an abortion clinic he operated in Northwest Washington.

Sherman, 65, is charged with second-degree murder in connection with the deah of the high school student. He also is charged with 26 counts of perjury in what the government says was an attempt to cover up the cicumstances surrounding his treatment of Rita McDowell.

Blake testified yesterday that his notes and McDowell's physical condition indicated that she was 16 weeks pregnant at the time of the abortion. Earlier in Sherman's trial, a government expert had testified that medical standards recommend that abortions after the 12th week of pregnancy should be performed in a hospital, not a clinic, because of the risk of complications.

During cross-examination by defense attorney Robert F. Muse, Blake testified that when McDowell was admitted to the hospital, he had described her, in his notes, as conscious, able to talk, and in "moderate distress."

Blake, who was in his second year of hospital residency in March 1975, treated McDowell during the first three hours of her hospitalizaion, according to yesterday's testimony. He now lives in Alabama.

Muse, in his opening statement to the jury, said that defense evidence would show that McDowell's death resulted from grossly negligent treatment at D.C. General, and not because of Sherman's treatment.

Blake also testified under cross-examination that his notes showed that McDowell had begun to experience bleeding the day before she visited Sherman's office. He also told the jury that there were no notations in his records to indicate use of medical instruments on McDowell.

Earlier yesterday, Rita's mother Lupe M. McDowll, who accompanied her daughter to Sherman's clinic, testified that "no one" told her of any problems with Rita's abortion.

In a dramatic, emotional court session Tuesday afternoon, McDowell described the circumstances that ended with her daughter's death. Her testimony was interrupted at one point when she collapsed into tears.

Yesterday, McDowell testified "the only thing they told me (at the clinic) was that the baby would come down (that night). That was it. The day after the procedure, when Rita became ill, McDowell told the crowd that she telephoned Sherman's office and was told by a woman there to bring Rita back to the clinic two days later - one day after a scheduled appointment, which McDowell presumed was canceled.

"I figured he (Sherman) knew what he was doing," McDowell testified during cross-examination by defense lawyers Constance O'Bryant. Prior to her hospital admission. Blake is expected to continue his testimony today.

". . . My daughter didn't complain she was that sick. She just laid in bed," McDowell responded when asked by O'Bryant why Rita wasn't taken to a hospital earlier. McDowell told the jury she thought that Rita could wait the extra day to see Sherman. McDowell works part-time as a housekeeper for Ethel Kennedy, widow of the senator.

Defense attorneys vigorously protested when McDowell later disclosed that Rita's son, Tony, now 5, had received $300,000 as a result of a medical malpractice suit filed against Sherman after Tony's mother's death.

"He got everyting," Mrs. McDowell testified during questioning by Principal Assistant U.S. Attorney Carl S. Rauh.

After defense lawyers contended that the statement was prejudicial to Sherman and warranted a motion for a mistrial, Superior Court Judge Fred B. Ugast instructed the jury of seven women and five men that information they heard about the resolution of the lawsuit was not to be considered in their judgment of Sherman's guilt or innocence.